Multi-item detector

ABSTRACT

Apparatus for detecting the occurrence of a simultaneous multiple feed of documents when a vacuum source operates on documents being carried away from a document feeder so as to attract the documents toward a sensing station having an exhaust port for positive air pressure. A multiple feed of documents increases the pressure at the exhaust port. A pressure sensing device is coupled to the exhaust port for detecting such increase in pressure, thereby detecting a multiple feed of documents.

United States Patent lnventors Ernest L. Staples, Jr.;

Albert R. Clark; Victor M. Moreland, all of Dallas, Tex.

Appl. No. 793,300

Filed Jan. 23, 1969 Patented June 29, 1971 Assignee RecognitionEquipment Incorporated Dallas, Tex.

MULTl-[TEM DETECTOR 8 Claims, 5 Drawing Figs.

U.S. Cl 271/56, 73/37.7

Int. Cl B65h 7/02 Field of Search 271/56, 47,

[56] References Cited UNlTED STATES PATENTS 2,712,870 7/1955 Geertsen271/64 2,994,528 8/1961 Hull et al. 271/56 3,232,095 2/1966 Symnoski73/37.5 3,439,536 4/1969 Cushman 73/377 X Primary Examiner-J. WegbreitAtt0rneyRichards, Harris & Hubbard ABSTRACT: Apparatus for detecting theoccurrence of a simultaneous multiple feed of documents when a vacuumsource operates on documents being carried away from a document feederso as to attract the documents toward a sensing station having anexhaust port for positive air pressure. A multiple feed of documentsincreases the pressure at the exhaust port. A pressure sensing device iscoupled to the exhaust port for detecting such increase in pressure,thereby detecting a multiple feed of documents.

PATENTED JUN29I97| 3589.714

SHEET 0F 2 DOCUMENT i FEEDER 49 DOCUMENT /AMP SORTER INVENTORS:

26 ALBERT R. CLARK ERNEST L. STAPLES, JR. FIG. 2 VICTOR M. MOR' ANDATTORNEY I00 IOb I I I! E M I 2 53 I 23 INVENTORS l1 ALBERT R. CLARK 25ERNEST L.STAPLES, JR. 5 VICTOR M. MOR ND ATTORNEY MULTI-ITEM DETECTORThis invention relates to document feeding and more particularly tosensing the passage of more than one document at a time along a documenttravel path.

BACKGROUND OF THE INVENTION Systems have heretofore been developed forfeeding documents into document handling systems such as documentsorting devices and document reading devices. .Such documents may take avariety of forms, such as relatively thick punched cards and relativelythick bank checks.

Document feeders may operate at extremely high speeds and feed documentsone at a time through a conveyor to a handling system. A high-speeddocument feeder is disclosed in US. Pat. No. 3,300,207. While suchdocument feeders have been developed so as to minimize thefeeding ofmore than one document at a time into the conveyor, a problem ariseswhen more than one document at a time reaches the document handlingstation. A need, therefore, exists for detecting the multiple feeding ofdocuments so that appropriate operations may be performed by the systemeither to prevent the multiple fed documents from reaching the documenthandling station or to allow the document handling station to reject themultiple fed documents.

In the prior art, vacuum sensing means have been placed on oppositesides of a document pathway such that a multiple feed of documents isdetected by the contraction and expansion of bellows used in conjunctionwith the vacuum air source. The effect of various and intermixed weightsand flexibilities of the documents uponthe vacuum sensing means and ofslight variations in the separation vacuum (which also operates thebellows) has made such a method of detection highly unreliable. A need,therefore, exists 'for a reliable system of detecting the multiplefeeding of documents which is independent of the physicalcharacteristics of the documents or of the adjustment of the vacuumsensing means.

In accordance with the present invention, a vacuum field is applied onopposite sides of a document pathway and a positive airfield is appliedin the zone of the vacuum fields. Multiple fed documents, when attractedby the vacuum fields, cause an increase in pressure in the positiveairfield which is sensed.

More particularly a pair of document sensing blocks are located on eachside of a document pathway having apertures to which a vacuum is appliedand having an exhaust port through which air under positive pressureflows. A fluid-detecting device is coupled to the sensing blocks forsensing an increase in the positive pressure at the exhaust ports whendocuments simultaneously are drawn to both sensing blocks.-

Preferably air under positive pressure flows to two channels. Onechannel allows air to exit out of the exhaust .port of each block memberfacing the document pathway, while the other channel simultaneouslyapplies positive air pressure to a pressure detecting device. As airflows in, the first of said channels is impeded by multiple feddocuments .being attracted toward both blocks simultaneously by thevacuum pressure, the positive pressure will increase in the second ofsaid channels leading to the fluid-detecting device.

DESCRIPTION OF THE DRAWINGS For a further understanding of theinvention, reference may now be had to the following description inconjunction with the accompanying drawings in which:

FIG. 1 illustrates the present document processing system and includes aperspective view of document sensing means;

FIG. 2 is a sectional view of the document sensing means taken generallyalong the section lines 2-2 of FIG. 1 and along section lines 2-2 ofFIG. 3;

FIG. 3 is a perspective view of the bottom of the sensor plate;

FIG. 4 is a top view of the bottom plate; and

FIG. 5 is a schematic plan view'illustrating the operational aspects ofthe document sensing means upon documents carried bv the belt transportsvstem.

THE PREFERRED EMBODIMENTS In FIG. 1, a document 10 is transported by adual belt transport system 11 (fragmentarily shown) from a documentfeeder 12 to a document sorter 13. A suitable feeder is described'inU.S. Pat. No. 3,300,207. As the document is advanced by the belttransport system, it passes between document sensor blocks 14 and 15located on opposite sides of the document pathway.

In the sectional view of FIG. 2, sensor blocks 14 and 15 are shown to beidentical. Both are mounted on an upper baseplate 19 which in turn ismounted on a lower baseplate 21. Face 16a of sensor block '14 faces oneside of document 10 while face 16b of sensor block 15 faces the otherside. As a document is passed between faces 16a and 1619 it moves pastmultiple apertures 17a and 17b respectively. Apertures 17a and 17b leadto channels 18a and 18b. Channels 18a and 18b exit through the base ofblocks 14 and 15 respectively and interconnect with each other in plate19 so as to form a single channel 20 which exits through the bottom ofplate 19 and interconnects with channel 22 in baseplate 21.

A vacuum source 24 is connected to the bottom of baseplate 21 through ahose 23. Vacuum source 24 may be of the type manufactured by The SingerCompany, Diehl Division, Somerville, New Jersey and identified as ModelFl32l-VOR925-l. A vacuum of approximately 20 inches of water is drawn insensor blocks 14 and 15 through apertures 17a and 17b. Exhaust airpasses from sensor blocks 14 and 15 by way of channels 18a and 18b intochannel 20 of sensor plate 19, passes from plate 19 by way of channel 20into channel 22'of baseplate 21, and thence to the vacuum supply 24 byway of hose 23. The function of such vacuum source will be describedlater.

A positive pressure air source 25 is also connected to baseplate 21 byway of hose 26. The airflow passes through baseplate 21 by way'ofchannel 27 and interconnects with channel 28 of plate 19. Channel 28 isformed such that the portion 281: is of the same radius as channel 27.

Plate 19 has a network of channels or grooves in the bottom thereof asshown in FIG. 3. Channel 28 communicates with channels 29, 30 and 31.Channels 29 and 30 communicate with vertical channels 32 and 33respectively which in turn communicate with channels 350 and 35d insensor blocks 14 and 15 respectively. Channels 35c and 35d lead toexhaust ports 35a and 35b respectively. I

In a preferred embodiment, the document belt transport 11, FIGS. 1 and5, conveys documents from a document feeder 12 along a pathway betweenfaces 16;: and 16b of sensor blocks 14 and 15 respectively. Thetransport belts pass above sensor blocks 14 and 15. Documents aregrasped by the belts so that the lower portion margins are belowapertures 17a and 17b.

The vacuum supply source 24 causes airflow into sensor blocks 14 and 15through apertures 17a and 17b. The positive pressure source 25 causesairflow to exit out of sensor blocks 14 and 15 through exhaust ports 35aand 35b. Should two documents be transported simultaneously by thesensor blocks 14 and 15, they will be diverted from a pathwayimmediately as they pass the two blocks. More particularly they will bedrawn by vacuum into contact with the faces of blocks 14 and 15. Forexample, in FIG. 5 document 10a is sucked by the vacuum against the faceof block 14 and obstructs the flow of air out of exhaust port 35a whiledocument 10b is sucked by the vacuum against the face of block 15 andobstructs the flow of air out of exhaust port 35b. The resultantobstruction of airflow from channel 28 into channels 29 and 30 causes anincrease in pressure in channel 31 preferably to the equivalent ofapproximately an 8-inch column of water. Channel 31 leads 35 of sensorplate 19. Channel 35 is formed such that the end of channel 35 whichinterconnects with channel 34 is of the same radius as channel 34. Theopposite end of channel 35 is constrictive so as to create a power jet35:: through which the airflow exits out of channel 35. As the airflowemerges from power jet 35e it enters mixing zone 36.

Channels 31 and 37 lead into mixing zone 36 perpendicularly and onopposite sides of the airflow out of power jet 350. Channel 31 narrowsits point of entrance into the mixing zone so that it is approximatelyone-half the diameter of channel 37. Horizontal channel 37 interconnectswith vertical channel 38 which exits out of the top of plate 19 into theatmosphere.

As the airflow emerges from power jet 35c it attaches, because of theCoanda effect, to wall 40 which is directly opposite the entrance ofchannel 37 and the mixing zone 36. The effect of ambient air-pressure onmixing zone 36 by way of channel 37 reduces the pressure between theairflow from the power jet 35e and wall 40. Because of this lowerpressure, the airflow bends toward and eventually attaches to wall 40.The result is that the airflow stream becomes stable in the attachedposition. The airflow stream, attached to wall 40 because the Coandaeffect, thereby flows into channel 41.

Channel 31 is constricted so as to create a control jet 31a throughwhich airflow exits out of channel 31 into mixing zone 36. So long asonly one document at a time is transported past sensor blocks 14 and 15,the pressure in channel 31 is minimal and the airflow out of thepowerjet 35a will attach to wall 40.

When a multiple feed occurs, the pressure in channel 31 reaches athreshold level of approximately 8 inches of water due to theobstruction of exhaust ports 35a and 35b by the documents and theairflow out of the control jet 31a is sufficient to break the Coandaefiect and switches the airflow out of the power jet from channel 41into channel 42. When the pressure in channel 31 returns below thethreshold level, the airflow from the power jet switches from channel 42back into channel 41. I

Flush mounted to plate 19 at the end of channel 41 is apressure-sensitive transistor 43. Transistor 43 may be of the typemanufactured by Stow Laboratories, lnc., of Stow, Massachusetts andidentified as PitranPT-l piezotransistor. As transistor 43 obstructs theexit of airflow out of channel a separate exit channel 44 isinterconnected with channel 41 such that the airflow from channel 41will pass through channel 44 into vertical channel 45 which exits out ofthe top of plate 19 into ambient air. The base, emitter and collectorleads of transistor 43 are coupled by way of channels 46, 47 and 48respectively to a suitable amplifier 49. Transistor 43 operates as aconventional input transistor in amplifier 49.

documents occurs the air pressure in channel 31 will reach the thresholdlevel of approximately 8 inches of water necessary to cause the airflowfrom control jet 31a to switch the airflow from power jet 35a fromchannel 41 to channel 42 which exits out of sensor plate 19 into ambientair. This decrease in air pressure in channel 41 from approximatelyone-half p.s.i. to zero is detected by the diaphragm of pressuresensitive transistor 43 so as to effect a change in the output ofamplifier 49.

The output of amplifier 49 is applied by way of channel 50 to documentsorter 13. When there is no multiple feed of documents, the output ofamplifier 49 applies a signal which causes the document sorter 13 toperform its normal function. Should there be a multiple feed ofdocuments, the output of amplifier 49 will cause the document sorter 13to pass all multiple fed documents into a reject pocket so that thesedocuments can be returned to the document feeder for subsequentreprocessing and sorting.

Having described the invention in connection with the foregoingembodiments thereof, it is to be understood that further modificationsmay now suggest themselves to those skilled in the art and it isintended to cover such modifications as fall within the scope of theappended claims.

What we claim is:

1. a multi-item detector for use in conjunction with a document feederwherein documents are fed past a sensing station comprising:

a. a pair of like sensing blocks forming a document pathway, each blockhaving apertures in juxtaposed faces through which a vacuum is applied,

b. a first port through which a fluid flows under a positive pressureinto the document pathway in the face of one of said sensing blockscoupled by a channel to a pressure source,

c. a second port through which a fluid flows under a positive pressureinto the document pathway in the face of the second of said sensingblocks coupled by a channel to the pressure source, and

d. a fluid-pressure-detecting device coupled to the channel leading toeach said ports for sensing an increase in the fluid pressure in saidchannel when the vacuum draws documents into contact with both of saidblocks.

2. The combination set forth in claim 1, in which said detecting deviceis a monostable fluid amplifier with means for sensing a change of stateof said amplifier to indicate the presence of a multiple feed ofdocuments.

3. The method of sensing a multiple feed of documents passing along adocument pathway which comprises:

a. establishing fluid suction fields on opposite sides of said pathway,

b. establishing primary fluid flow under a positive pressure on oppositesides of said pathway within the zones occupied by said suction field,and

c. sensing an increase in pressure in said fluid flow produced by twodocuments in said pathway responding to each of said suction fieldssimultaneously to impede both said flows.

4. The method of claim 3, in which said primary fluid flows are coupledto a pair of secondary fluid flows remote from said pathway and switchedbetween said pair when said primary flows are both impeded.

5. The method of claim 4, in which an electrical signal is produced whenpressure due to flow restriction in one of said secondary. flows exceedsa predetermined level.

6. A system for determining the occurrence of a multiple feed ofdocuments by a document feeder which comprises:

a. dual block members spaced apart on opposite sides of the documentpathway having multiple inner cavities with each such cavity opening atthe sides of the blocks facing the document pathway,

b. a vacuum supply means for supplying a vacuum to a portion of saidinner cavities in both block members simultaneously to draw documentspassing between the dual block members toward the cavity openings,

c. a positive pressure air supply means for supplying air underpressure,

(1. a first port through which a fluid flows under a positive pressureinto the document pathway in the face of one of said block memberscoupled by a channel to said positive pressure air supply means,

e. a second port through which a fluid flows under a positive pressureinto the document pathway in the face of the second of said blockmembers coupled by a channel to said positive pressure air supply means,and

.' a fluid-pressure-detecting device coupled to the channel leading toeach of said ports for sensing an increase in fluid pressure in saidchannel when said vacuum draws documents into contact with both of saiddual block members.

7. The combination set forth in claim 6, in which a document sortingmeans is responsive to the output of the detecting device for rejectingmultiple fed documents.

8. The combination set forth in claim 6, in which said pressuredetecting channel includes structure forming a forked flow path withairflow normally limited to one branch of said forked flow path andmeans for switching flow to the other branch when pressure thereinincreases and wherein a fluid pressure sensor is positioned in saidother branch.

1. A MULTI-ITEM DETECTOR FOR USE IN CONJUNCTION WITH A DOCUMENT FEEDERWHEREIN DOCUMENTS ARE FED PAST A SENSING STATION COMPRISING: A. A PAIROF LIKE SENSING BLOCKS FORMING A DOCUMENT PATHWAY, EACH BLOCK HAVINGAPERTURES IN JUXTAPOSED FACES THROUGH WHICH A VACUUM IS APPLIED, B. AFIRST PORT THROUGH WHICH A FLUID FLOWS UNDER A POSITIVE PRESSURE INTOTHE DOCUMENT PATHWAY IN THE FACE OF ONE OF SAID SENSING BLOCKS COUPLEDBY A CHANNEL TO A PRESSURE SOURCE, C. A SECOND PORT THROUGH WHICH AFLUID FLOWS UNDER A POSITIVE PRESSURE INTO THE DOCUMENT PATHWAY IN THEFACE OF THE SECOND OF SAID SENSING BLOCKS COUPLED BY A CHANNEL TO THEPRESSURE SOURCE, AND D. A FLUID-PRESSURE-DETECTING DEVICE COUPLED TO THECHANNEL LEADING TO EACH SAID PORTS FOR SENSING AN INCREASE IN THE FLUIDPRESSURE IN SAID CHANNEL WHEN THE VACUUM DRAWS DOCUMENTS INTO CONTACTWITH BOTH OF SAID BLOCKS.
 2. The combination set forth in claim 1, inwhich said detecting device is a monostable fluid amplifier with meansfor sensing a change of state of said amplifier to indicate the presenceof a multiple feed of documents.
 3. The method of sensing a multiplefeed of documents passing along a document pathway which comprises: a.establishing fluid suction fields on opposite sides of said pathway, b.establishing primary fluid flow under a positive pressure on oppositesides of said pathway within the zones occupied by said suction field,and c. sensing an increase in pressure in said fluid flow produced bytwo documents in said pathway responding to each of said suction fieldssimultaneously to impede both said flows.
 4. The method of claim 3, inwhich said primary fluid flows are coupled to a pair of secondary fluidflows remote from said pathway and switched between said pair when saidprimary flows are both impeded.
 5. The method of claim 4, in which anelectrical signal is produced when pressure due to flow restriction inone of said secondary flows exceeds a predetermined level.
 6. A systemfor determining the occurrence of a multiple feed of documents by adocument feeder which comprises: a. dual block members spaced apart onopposite sides of the document pathway having multiple inner cavitieswith each such cavity opening at the sides of the blocks facing thedocument pathway, b. a vacuum supply means for supplying a vacuum to aportion of said inner cavities in both block members simultaneously todraw documents passing between the dual block members toward the cavityopenings, c. a positive pressure air supply means for supplying airunder pressure, d. a first port through which a fluid flows under apositive pressure into the document pathway in the face of one of saidblock members coupled by a channel to said positive pressure air supplymeans, e. a second port through which a fluid flows under a positivepressure into the document pathway in the face of the second of saidblock members coupled by a channel to said positive pressure air supplymeans, and f. a fluid-pressure-detecting device coupled to the channelleading to each of said ports for sensing an increase in fluid pressurein said channel when said vacuum draws documents into contact with bothof said dual block members.
 7. The combination set forth in claim 6, inwhich a document sorting means is responsive to the output of thedetecting device for rejecting multiple fed documents.
 8. Thecombination set forth in claim 6, in which said pressure detectingchannel includes structure forming a forked flow path with airflownormally limited to one branch of said forked flow path and means forswitching flow to the other branch when pressure therein increases andwherein a fluid pressure sensor is positioned in said other branch.